1. Field of the Invention
The present invention relates to a vehicle security system having improved and decreased electrical power requirements due to a novel communications methodology.
2. Background
Vehicle security systems are used to prevent or to diminish the probability of theft to a vehicle or other object upon which they are deployed. While, many of these vehicle security systems adequately protect vehicles and other objects, they suffer from various drawbacks. For example and without limitation, many of these prior vehicle security systems require a relatively large amount or supply of electrical power which is usually provided by the vehicle battery. Such electrical power is required, for example, to maintain the readiness or functionality of the system receiver in order that the system be capable of responding to a transmitted signal at, what appears to the user to be, at all times.
Electrical power is also required to maintain the operability of the other and various system components such as, and without limitation, the shock sensor. Notwithstanding all of the power needed to maintain the operational readiness of these other vehicle security system components, it is widely recognized that most of the required electrical power is typically expended by the receiver. In fact, power is required by the receiver at all the times regardless of the xe2x80x9carmedxe2x80x9d or xe2x80x9cdisarmedxe2x80x9d state of the system. Normally more power is needed when the receiver is placed into an xe2x80x9cactivatedxe2x80x9d state then when placed into a xe2x80x9cwaitingxe2x80x9d or xe2x80x9cambient statexe2x80x9d. Failure to provide such electrical power to the receiver, typically causes the entire vehicle security system to become inoperative, a rather unacceptable circumstance.
Oftentimes vehicles having such security systems are parked for relatively large periods of time at an airport or other various locations. In such situations, many of these prior vehicle security systems cause the vehicle battery to become discharged due to the relatively large amount of power which was and is required by these vehicle security systems and due to the stationary nature of the parked vehicle which prevents the vehicle""s alternator assembly from recharging the battery. In such situations, a user returns to the car, usually from a long trip, only to discover that the vehicle has become disabled and that the vehicle will not start. Such a situation is, of course most, highly undesirable and potentially dangerous.
There is therefore a need for a new and improved vehicle security system having improved power requirements and further having a new and improved and substantially reduced electrical communication methodology which substantially reduces the overall amount of required electrical power by reducing the amount of time over which the receiver must draw power in order to allow the user to reliably activate and/or operate the vehicle security system.
It is the first object of the invention to provide a vehicle security system which requires and/or draws a relatively low amount of electrical power and which overcomes some or all the drawbacks and/or deficiencies of the previously delineated prior vehicle security systems.
It is a second object of the invention to provide a new and useful vehicle security system having a new and improved communication methodology which reduces the amount of electrical power consumed by these systems.
It is a third object of this invention to provide a new and improve vehicle security system having a processor, operating under stored program control, which is activated or is adapted to draw electrical energy and/or power at levels sufficient to activate the processor only for certain time intervals of a relatively short duration of time.
According to a first aspect of the present invention, a vehicle security system is provided. The vehicle security system includes a transmitter which is adapted to selectively generate a signal having a plurality of evenly spaced preamble bits that are followed by several relatively closely spaced guard bits and at least one code word;
a receiver adapted to receive the signal and in response to the receipt of the signal to generate a second signal; and
a processor coupled to the receiver and adapted to receive the second signal, and in response to the receipt of the second signal to enter an xe2x80x9carmed modexe2x80x9d.
According to a second aspect of the present invention, a method is provided which is effective to substantially reduce the amount of electrical power consumed by a vehicle security system of the type having a transmitter and receiver, wherein the transmitter is adapted to generate and communicate certain signals to the receiver when the receiver is activated and wherein the receiver is adapted to receive the certain signals and to consume electrical power when activated. The method, according to this second aspect of the present invention, comprises the steps of causing the certain signal to have the plurality of evenly spaced preamble bits followed by several relatively closely spaced guard bits and at least one code word; and
activating the receiver for an interval of time equal to the interval of time between two adjacent bits of the plurality of the evenly spaced preamble bits and continuing to maintain the activation of the receiver only if the receiver receives one of the plurality of preamble bits during the interval of time, thereby reducing the amount of electrical power consumed by the receiver.
Further objects, features, and the advantages of the present invention will become apparent from a consideration of the following description and the appended claims.